Braking generator for use with calender



1935- c. w. DRAKE ET AL, 1, 7

BRAKING GENERATOR FOR USE WITH CALENDER Filed May 11, 1935 WITNESSES: INVENTORS.

Chester W Drake, and

v Horgz ce E Nason 0w! Patented Jan. 15, I935 UNITED STATES PATENT OFFICE BRAKING GENERATOR. FOR USE WITH CALENDER Chester W. Drake,

Irwin, and Horace E. Nason,

Application May 11, 1933, Serial No. 670,496

6 Claims.

This invention relates to a system of control for governing the operating characteristics of a plurality of dynamo electric machines.

More particularly, this invention relates to an electric control system for governing the operation of the motors utilized in a paper machine for driving a calender, a supply reel, 2. winder reel, and the tension means provided with the supply reel.

It is an object of this invention to maintain a constant tension in material, such as paper, rubber, flexible material, cloth, or any other material subjected to a process similar to the process hereinafter described and passing from one point to another of the machine.

Another object of this invention is to selectively control the tension of the paper or other material in the winding machine.

A further object of this invention is to maintain any selected tension in material, such as paper, rubber, flexible fabric, etc., in passing through a machine performing an operation thereon.

It is also an object of this invention to provide a calender and winder drive and control system therefor that shall be simple in construction and efiicient in operation.

Other objects of this invention will become apparent to those skilled in the art, from a study of the following description when taken in conjunction with the accompanying drawing, in which there is shown a diagrammatic representation of the features embodying this invention.

Referring to the drawing, the reference character 50 designates a supply reel for the paper 51, which is to pass through the calender 52 to the winder reel 54. A tension indicating device 53 is disposed intermediate the calender 52 and the winder reel 54. The winder reel 54 is driven by 40 a motor 55 in a suitable manner. The calender is driven by a calender motor 57 which may have its primary winding 58 supplied with energy from a source 45 of alternating current energy of low frequency or a source 44 of alternating current of high frequency not shown. The secondary winding 59 of the calender motor 57 is provided with a controller 56 for varying the speed of the motor in a suitable manner.

Duringnormal operation of the entire sys-,

5 through the calender 52 to the winder reel 54, the motor 57 is supplied with energy of a very low frequency from the low frequency supply 45. Contactors 25 and 28 are ,so arranged or interlooked that when contactor 28 is closed, contactor 25 cannot be closed and when contactor b 25 is closed, contactor 28 cannot be closed.

For a more detailed explanation of the system of operation exclusive of the means for providing tension in the material 51 between the supply reel 50 and the calender 52, reference may be had to the patent application of Chester W. Drake, Serial No. 574,275, filed Nov. 11, 1931, relating to Synchronous motor drive for supercalenders and winders. It is not believed that a detailed discussion of the method of operation of the winder reel and the calender is here necessary, since these elements do not in themselves form a part of this invention, but this invention resides par ticularly in the means for providing a desirable operation for the supply reel 50 during the threading operation and the necessary tension on the material 51 between the calender and the supply reel during normal operation.

The supply reel 50 is provided with a braking generator 10 which, during normal operation, restrains the rotation of the supply reel 50 thereby supplying the material 51 to the calender 52 under a desired tension. It is nearly always necessary, during the threading operation, that the supply reel be positively driven to release the tension. This may be accomplished by operating the braking generator 10 as a motor to drive thereel 50 to unwind the material.

In order that the energy of the braking generator 10, during normal operation, may not be lost, the braking generator is connected in series circuit relation with a series motor 31. A booster generator 33 is disposed in series circuit relation with the braking generator 10 and the series motor 31. The field winding 37 of the booster generator is provided with a field reversing rheostat 62, so that the voltage generated by the booster generator may either add to or subtract from the voltage in the series circuit for the braking generator 10 and series motor 31.

To control the voltage of the braking generator 10, a regulator 4 is provided. The regulator 4 is suitably-interconnected with the buses 1 and 7 in a manner explained more in detail hereinafter.

It should be understood that the specific motor 50 57 and control associated therewith are not a necessary part of this invention. It is suflicient if any variable speed drive for the calender is used. Further, the series motor 31 need not be mounted on the shaft of the calender motor. The 55 as to operate at a speed substantially proportional to either the reel motor or the calender motor. If arranged to operate in such manner, the tension in the material will, for any given diameter of roll 50, remain substantially constant.

A better understanding of the novel features of this invention may be had from a study of the sequence of operation during normal threading operation and normal full speed operation of the calender and winder. If buses 1 and 7 are suitably energized from a source of direct current, not shown, a circuit is established from bus 1 through conductor 2, main coil 3 of voltage regulator 4, resistor 5 and resistor 6 to the bus '7. The regulator 4 is associated with the field winding 9 of the braking generator 10 and automatically regulates the voltage of the braking generator in a well known manner, during normal full speed operation, to put a substantially constant tension on the material 51 between the supply reel 50 and the calender 52.

During the threading operation the braking generator 10 is made to operate as a motor, whereby the threading operation may be very much facilitated. Since the calender motor 5'? operates very slowly during the threading operation, namely, is supplied with energy from the lowfrequency source 45 through the contactor 28, the contact members 46 are open, thereby keeping the movable coil 49 of the regulator 4 deenergized. When the movable coil 49 is deenergized, the spring 18 of the regulator 4 keeps the contact members closed, thereby connecting the field winding 9 across the buses 1 and 7. The circuit for the field 9 may be traced from bus 1 through conductors 8 and 11, resistors 12 and 6, in parallel to resistors 19 and 1'7, to the bus '7. It is thus obvious that the braking generator has its field winding 9 excited a maximum amount.

To accomplish the threading operation, the arm 61 of the field reversing rheostat 62 is moved from its neutral or vertical position to the position shown, thereby energizing the field winding 37 of the booster generator 33 in a direction indicated by the full-line arrow. The circuit for field winding 37 may be traced from bus 1 through conductor 8, controller segments 35 and 36, bridged by arm 61, the field winding 37, controller segment 38, a portion 39 of the resistor 40, and conductor 41 to the bus 7.

If the voltage of the booster generator 33 is desired to be in the opposite direction, the arm 61 is, of-course, moved towards the right thereby utilizing resistor 43 and controller segment 42 and energizing the field winding 37 in the direction indicated by the dotted line arrow.

The booster generator 33 is driven at a constant speed by a suitable motor such as 34.

While the foregoing discussion goes into some detail as to the method of supplying either a positive or a negative voltage in the series circuit for the braking generator 10 and series motor 31 at the terminals of the booster generator 33, it is, of course, obvious to those skilled in the art from the teachings of this invention that a number of other electrical means can be utilized for varying the voltage either positively or negatively in the series circuit mentioned. Applicants do not wish to be limited to the specific bposter generator shown nor the specific field reversing field rheostat 62 shown, but believe that it is within the spirit of this invention that any voltagevarying means may be utilized.

To effect the proper operation'of the braking I series motor may be connected in any manner so generator 10, switch 23 is closed, thereby energizing the actuating coil 24 of the series contactor 26. Closure of the contactor 26 establishes a series circuit through conductor 27, resistor 29, field winding 30 of the series motor 31, conductor 32, braking generator 10 and booster generator 33 to the contactor 26. The braking generator 10 is thus caused to operate as a motor by means of the energy supplied by the booster generator 33 and drives the supply reel 50 in such a direction that the threading operation through the calender 52 and on the winder reel 54 may be readily performed. During this threading operation, the voltage of the series motor 31 is not of high value, since this motor is operating at a very low speed.

Once the threading operation has been completed, the contactor 28 is deenergized and the contactor 25 is energized, thereby supplying the motor 57 with alternating current of a high-frequency' from source 44 and closing a parallel circuit to the resistor 29, which parallel circuit extends from the left-hand terminal of the resistor 29 through back contact members 46 of the contactor 28, variable resistor 47, conductor 48, movable coil 49 of the regulator 4 and conductor 60 to the other or right-hand terminal of the resistor 29. The arm 61 may now be placed to the neutral position so that the voltage of the booster generator 33 is negligiblaand the braking generator, now being driven by the supply reel at a constant speed, provides the necessary tension to the material 51, and in so doing supplies energy to the series motor 31 which aids the motor 57 to operate the calender 52. The efliciency of the system is thus materially increased, sinceno energy is lost in wastefully heating a resistor that might be utilized with the braking generator 10.

Since the movable coil 49 is connected across the resistor 29, the regulator armature 14 will vibrate, breaking the circuit through conductor 13 and armature 14 at contact member 15 and also closing the circuit at the contact member 15'. The rate of vibration will depend upon the voltage drop across the resistor 29 and the regulator will excite the field winding 9 of the braking generator 10 in such a manner that substantially constant current will be maintained in the armature circuit of the braking generator, thus providing a substantially constant tension in the material regardless of the speed of the braking generator.

The capacitors and 22 and the resistor 21, shown associated with the regulator, are for the purpose of preventing destruction of the contact members of the regulator by the arcs occasioned by the rapid vibration or opening of the contact members. To selectively vary the tension of the material, the movable coil 49 of the regulator 4 is connected in series circuit relation with the variable resistor 4'7. Variation of the efiective resistance of the resistor 47 definitely fixes the tension in the material 51.

The diagrammatic showing made of this invention and the description hereinbefore made are merely illustrative. Others skilled in the art, after having had the benefit of the teachings of this invention, can readily devise other circuit arrangements for providing the necessary tension in the material between the supply reel and the calender. Applicants, therefore, do not wish to be limited to the specific showing herein made but wish only to be limited by the scope of the appended claims and the pertinent prior art.

I ,We claim as our invention:

1. In a calender and winder drive, a calender motor, a series motor on the shaft of the calender motor, a supply reel having a shaft, a braking generator on the shaft of the supply reel, means for connecting said series motor and braking generator in series circuit relation, and means including a booster generator for varying the voltage in said series circuit to cause said braking generator to operate as a motor.

2. In a calender and winder drive, a calender motor, a series motor on the shaft of the calender motor, a supply reel having a shaft, a braking dynamo-electric machine on the shaft of the supply reel, means whereby said series motor and dynamo-electric machine are connected in series circuit relation, and selecting means including a booster generator for selectively varying the voltage in said series circuit to cause said dynamoelectric machine to operate either as a motor or as a generator.

3. In an electric system of control for a plurality of dynamo-electric machines, means for connecting all of said machines in series circuit relation, means for varying the speed of one machine, selective voltage control means for one of the machines the speed of which is not to be controlled whereby the machine, the speed of which is to be varied, may be caused to operate as a motor, or as a generator, and means responsive to the operating characteristics of one of said plurality of machines to maintain the torque, of the machine the speed of which is varied, constant.

4. In an electric system of control for a pair of dynamo-electric machines, means for connecting the armatures of said machines in series circuit relation, means for varying the speed of one machine, means for varying the voltage of the other machine from a predetermined positive to a predetermined negative value to thus cause said machine, the speed of which is to be varied, to operate either as a motor or as a generator, and means for controlling the excitation of the speedcontrolled machine when operating as a generator for developing a constant torque therein.

5. In an electric system of control for a dynamoelectric machine, operating means for positively driving said machine at varying speeds, selective voltage control means for the armature circuit of said machine whereby said machine may be caused to operate selectively as a motor or as a generator, and means for controlling the excitation of said machine to maintain the driving torque of said machine substantially constant regardless oi the variations in speed.

6. In an electric system of control for a calender and winder drive, a calender motor, a motor on the shaft of the calender motor, a supply reel having a shaft, a braking generator on the shaft of the supply reel, a booster generator, means for connecting the motor on the shaft of the calender motor, the braking generator and the booster generator in series circuit relation, means for varying the voltage of the booster generator from a predetermined positive value to a predetermined negative value to thus operate the braking generator as a motor to drive the supply reel or as a generator to brake the rotation of the supply reel, and means for maintaining the braking action of the braking generator substantially constant regardless of the speed of the supply reel.

CHESTER W. DRAKE. HORACE E. NASON. 

